Environmental correlates of taxonomic and phylogenetic diversity in the Atlantic Forest

Aim: There is little consensus on which environmental variables are best
at predicting multiple dimensions of diversity. We ask whether there are
common environmental correlates of diversity, despite ecological
differences, across nine clades of plants and animals distributed along a
single rainforest domain. For that, we the compare environmental
correlates of species richness, phylogenetic diversity, and phylogenetic
endemism. Location: Brazilian Atlantic Forest Taxon: Five clades of
plants: one within the Bromelioideae subfamily, three in the family
Melastomataceae (the Miconieae tribe, the genus Bertolonia, and the tribe
Cambessedesieae), and one in the family Bignoniaceae ( Fridericia and
allies). Four clades of animals: clearwing butterflies of the tribe
Ithomiini, treefrogs of the genus Boana, horned frogs of the genus
Proceratophrys, and birds in the subfamily Thraupinae. Methods: Using
curated occurrence localities and phylogenetic data, we generated maps of
(i) species richness, (ii) phylogenetic diversity, (iii) residuals of
phylogenetic diversity regressed on species richness, and (iv)
phylogenetic endemism for all groups. We also compiled a set of 30
environmental descriptors including records of current temperature and
precipitation, climatic stability over time, and topography. Through a
machine learning framework, we explored the environmental correlates of
each of these diversity measures for each group. Results:  The
environmental variables used here were strong predictors of diversity for
all studied groups. However, models for phylogenetic endemism had lower
predictive power. Although patterns of diversity are different among
groups, correlates of diversity are consistent across taxa. For both
species richness and phylogenetic diversity, current precipitation and
precipitation stability over time were consistently ranked among the
variables that strongly correlate with diversity patterns. The correlates
of phylogenetic endemism were less homogenous across groups. The results
also suggest that including climate stability over time is important when
predicting diversity measures that reflect historical components. Main
conclusions: Investigating environmental correlates of diversity for
multiple clades and diversity measures in a single geographic area allows
for a better understanding of common patterns across taxa. In this study,
we identified common environmental correlates of the patterns of species
richness and phylogenetic diversity, but not of phylogenetic endemism,
across different Atlantic Forest groups.